Jagadish Chandra Bose

“ The land from which I come did at one time strive to extend human knowledge, but that was many centuries ago. It is now the privilege of the West to lead in this work. I would fain hope, and I am sure I am echoing your sentiments, that a time may come when the East, too, will take her part in this glorious undertaking; and that at no distant time it shall neither be the West nor the East, but both the East and the West, that will work together, each taking her share in extending the boundaries of knowledge, and bringing out the manifold blessings that follow in its train. ”

“ The most prominent motile organ in Mimosa consists of a mass of tissue known as the pulvinus, at the joint or articulation of the primary leaf-stalk. The swollen mass on the lower side of this organ is very conspicuous. Under excitation the parenchyma, in this more effective lower half, undergoes 'contraction,' in consequence of which there is a fall of the leaf. This sudden movement constitutes the mechanical response of the leaf to the impinging stimulus, just as the contractile movement of a muscle in similar circumstances forms its characteristic mechanical response. ”

“ It is thus seen that the curve of electromotive variation due to radiation is similar to that obtained by the conductivity variation method.
It has already been shown that when the range of electric elasticity of the substance is not narrow, or when the strain is not too great, there is a recovery. That on subjecting the substance to the continued action of radiation there is a limiting effect; that too long continued action tends to produce an electric reversal; that too feeble an intensity may also produce a reversed effect. ”

“ The effect of weak solution is sometimes the opposite to that of strong solution. By touching different points of the wire with different reagents, the excitability of these portions are rendered unequal. Hence a resultant electromotive variation may be obtained by Vibrating the wire as a whole. The current in the Wire is from the less to the more excitable. By this method, invisible traces of physico-chemical change in a wire may be detected. Chemical reagents not only change the excitability but the quickness of response. ”

“ As long as it is alive, so long will it respond and recover, being ready again for a new response. This brief disturbance of the living poise, to be immediately restored to equilibrium of itself, is quite unlike the rolling of a stone downhill from a push. For the stone cannot regain its original position; but the living tissue at once reasserts its first stable poise on the cessation of stimulus. Thus a muscle, as long as it is alive, remains ever-responsive. ”

“ There are many important problems which wait for their solution till some such means of inquiry is found. What, for instance, are the various forms of stimulus which evoke an answering reaction in the plant? Again, has a given plant-tissue, like animal muscle, any definite perception-period capable of exact measurement? Is the responding tissue susceptible of fatigue? Is the intensity of its answer dependent on the intensity of the blow? Is the excitation that may be caused at one point transmissible to a distance, as along animal nerve? ”

“ The stimulus of unvarying intensity must also be made to act automatically upon the specimen. Under these conditions any variation that may be observed in the record will be due to changes of excitability induced as an after-effect of the stimulus itself.
Maintaining the stimulus-intensity absolutely constant is not so easy to secure with a single make- or break-shock, since the intensity of such a shock is liable to variation, according to the degree of suddenness with which it is effected; but the total additive value of a group of such shocks may be expected to be fairly constant. ”

“ If one merely wishes to produce response in a receiver at a distance, the more energetic the vibration is, the more likely it is to overcome obstacles. The waves may with advantage be of large size, as they possess very great penetrative power. The surface or the depth of the sensitive layer in the receiver may be extended, for if one part of it does not respond another part will. But for electro-optical investigations the conditions to be fulfilled are quite different. Too great an intensity of radiation makes it almost impossible to prevent the disturbance due to stray radiation. ”

“ A plant may be killed by subjecting it to a certain maximum temperature. The exact moment at which death is initiated is difficult to determine, since there has been found no certain and immediate criterion of death. One method by which the occurrence of death may be determined is by the abolition of that electric response which is characteristic of the living condition. A plant as long as it is alive gives in answer to a stimulus an electric response of galvanometric negativity. ”

“ If we excise an eye, say of a frog, and substitute a galvanometer in the visual circuit in the place of the perceiving brain, it is then found that each time a flash of light falls on the eye there is produced an electric response—that is to say, there is a sudden production of a current, which ceases on the cessation of light-stimulus. Stronger light produces stronger electric response in the galvanometer, just as it produces stronger visual sensation in the brain.
The visual circuit is therefore like an electric circuit. The retina is the sensitive element. The nerve is the conductor. ”

“ At the end of the series, however, where the maximum tonicity has been attained, the whole blow of the stimulus is utilised in giving external response, which now therefore is maximum. After this attainment of maximum excitability the usual fatigue-decline is seen to have taken place.
We must nevertheless be on our guard against drawing too hasty a conclusion, as regards the tonic condition, from the relaxation or contraction seen in the record; we should remember that a relaxed condition is not only indicative of a-tonicity, but may also be brought about by fatigue due to over-stimulation. ”

“ A muscle-curve registers the history of the fundamental molecular change produced by excitation in a living tissue, exactly as the curve of molecular reaction registers an analogous change in an inorganic substance. The two represent the same thing; in the latter the molecular upset is evidenced by the change of conductivity, while in the former it is manifested by the change of form. We have thus means of studying molecular reaction produced by stimulus of varying frequency, intensity and duration. An abyss separates the phenomena of living matter from those of inanimate matter. ”

“ In a very excitable condition we may suppose the slightest shock of stimulus would evoke a very large responsive expression; in a state of depression, on the other hand, the strongest stimulus would induce only a feeble reply. The relation between the stimulus and the response would thus form a gauge of the physiological condition of the organism. The invisible fluctuating changes taking place in the plant, under the changing conditions of the environment, might in this way be made to reveal themselves. ”

“ While the ethereal sea in which we are all immersed is being thus agitated by these multitudinous waves, we shall remain entirely unaffected, for we possess no organs of perception to respond to these waves. As the ether note rises still higher in pitch, we shall for a brief moment perceive a sensation of warmth. As the note still rises higher, our eye will begin to be affected, a red glimmer of light will be the first to make its appearance. From this point the few colours we see are comprised within a single octave of vibration, from about 400 to 800 billions in one second. ”

“ Certain changes take place when a living muscle is pinched or an electric shock passed through it. A responsive twitch is produced; the muscle is changed in form, becoming shorter and broader; the particles of the living substance are strained under the stimulus. The effect of the shock then disappears, and the muscle relaxes into its usual form.
This sudden change of form then, is one, but not the only mode of response of a living substance to external stimulus. Under external stimulation the muscle is thrown into a state of strain. On cessation of the stimulus it automatically recovers. ”

“ Imagine an unseen hand pressing the different keys in rapid succession. The ether notes will thus rise in frequency from one vibration in a second, to tens, to hundreds, to thousands, to hundreds of thousands, to millions, to millions of millions. ”

“ I exposed the bare leading wires to the strong action of the radiator by putting them in close proximity to the source of radiation, and yet no response was observed in the galvanometer. This freedom from disturbance is not due to the opposite action on the two wires, for a single wire may be exposed to the radiation without any action on the receiver.
With small radiators the intensity of radiation is not very great. This is a positive advantage in many experiments. It sometimes becomes necessary to have greater intensity without the attendant trouble inseparable from too long waves. ”

“ It would be impossible to analyse the resulting phenomenon unless a continuous record of changes in the intensity of light is secured with the same exactitude as that of variation of temperature. As regards these two principal factors, the effect induced by the rise of temperature is often antagonistic to that of increasing intensity of light. A rise of temperature, for example, enhances the rate of growth up to an optimum; light, on the other hand, acts as a stimulus in retardation of growth. ”

“ In the various investigations on the properties of electric waves, one property has not yet attracted so much attention as it deserves—the action of long ether waves in modifying the molecular structure of matter. Apart from the interest attached to the relation between ether, electricity, and matter, the subject is of importance as affording not only a very important verification of the identity of visible and electric radiation, but also establishing the continuity of all radiation phenomena. ”

“ We have seen how the strain effect of electric radiation was transient in some cases, whereas it was more persistent in others.
It is evident that in order to make the after-effect more or less permanent, and thus render it developable, self-recovery should be retarded. There are two ways in which the after-effect may be rendered comparatively permanent: (1) Even a highly elastic substance may be rendered more or less permanently distorted by straining it beyond the limit of elastic recovery; or (2) the presence of a retarding substance may prevent the self-recovery of the sensitive material. ”

“ When a substance is strained by radiation there is produced a sudden variation of conductivity. The substance automatically recovers from the strained condition (1) if it has not been overstrained by an excessive stimulus, or (2) if its electric elasticity is very great. I have found, in general, that after careful adjustment of the receiver it exhibits tendency towards self-recovery, if the intensity of incident radiation is not too strong. In the case of substances which are, electrically speaking, highly elastic, such as K, there is an automatic recovery even after strong stimulation. ”

“ I have hitherto preferred the null method in my experiments, as it possesses many advantages. The sensitiveness of the receiver can be pushed to the utmost extent, and observations taken when no effect is produced on the receiver. This method of total reflection also dispenses with the difficulty of making accurate measurement of the deviation produced. After obtaining the value of the index by the method described above, I wished to see whether it was not possible to obtain fairly good results by measuring the angle of refraction corresponding to a given angle of incidence. ”

“ As the frequency of vibration rises still higher, our organs of perception fail us completely; a great gap in our consciousness obliterates the rest. The brief flash of light is succeeded by unbroken darkness. ”